Sink spraying water when below-drain toilet pump kicks in

[Dsaile]

Hi all,
I have a friend who contacted me about a toilet in a new shop he is renting. The toilet is below the drain line, and has a pump. When he flushed the toilet, and the pump kicks in, water is spraying from somewhere beneath the sink. I don’t have a lot of experience with these types of toilets, and can’t figure out what’s happening here. Could anyone give any insight into what we’re dealing with here? Any help would be appreciated.

 

[SHEPLMBR]

PICTURES OF THE SET UP WOULD BE HELPFUL

 

[Dsaile]

PICTURES OF THE SET UP WOULD BE HELPFUL

Hi, thanks for checking in. I’m supposed to go over there next Monday, I’ll add pics as soon as I can. I’m just not sure why flushing the toilet would ever cause anything like that to happen. The pump is connected to the drain (obviously), but that’s apparently having some kind of effect on the cold water line under the sink. Pictures to come asap, thanks again.